What I need is:
-> After a user has successfully finished a survey -> my PHP Plugin should be fired.
-> in this PHP I should be able to read:
- surveyid (SID) - wich survey is finished?
- id (newly created id) of this survey record in survey_[SID] table

Other events are interessting also - like user: started, paused survey.
Many thanks for pointing me into the right direction!